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We report measurements of the Schottky barrier heights of Ni/Au contacts on Ga-polarity and N-polarity n-GaN under hydrostatic pressure and applied in-plane uniaxial stress. Under hydrostatic pressure the two different polarities of GaN yield significantly different rates of Schottky barrier height increase with increasing pressure. Uniaxial stress parallel to the surface affects the Schottky barrier height only minimally. The observed changes in barrier height under stress are attributed to a combination of band structure and piezoelectric effects. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Schottky barrier diodes, on both Ga and N faces of a ∼300-μm-thick free-standing GaN layer, grown by hydride vapor phase epitaxy (HVPE) on Al[sub 2]O[sub 3] followed by laser separation, were studied by capacitance-voltage and deep level transient spectroscopy (DLTS) measurements. From a 1/C[sup 2] vs V analysis, the barrier heights of Ni/Au Schottky contacts were determined to be different for the two polar faces: 1.27 eV for the Ga face, and 0.75 eV for the N face. In addition to the four common DLTS traps observed previously in other epitaxial GaN including HVPE-grown GaN a new trap B[sup ′] with activation energy E[sub T]=0.53 eV was found in the Ga-face sample. Also, trap E[sub 1] (E[sub T]=0.18 eV), believed to be related to the N vacancy, was found in the N-face sample, and trap C (E[sub T]=0.35 eV) was in the Ga-face sample. Trap C may have arisen from reactive-ion-etching damage. [ABSTRACT FROM AUTHOR]